SMMS is more symmetry, water repellency, bacterial resistance and durability than SMS. The SMMS is using 100% polypropylene as raw material with four-layer nonwoven: Spunbond+meltblown +meltblown+spunbondnon.
https://www.nonwoven-shuntai.com/spunbond-non-woven-fabric/hydrophilic-non-woven-fabric/smms-non-woven-fabric.html